Sweating and Hydrating 101

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water bottleWhen I run I sweat. . . a lot!

In fact, I once had an elderly lady at the YMCA approach me and ask, “Excuse me, um I was wondering, why do you sweat so much?”

Believe it or not this was not the only time people have noticed my well fuctioning eccrine glands.

So being a recognized expert when it comes to sweat, let me tell you how to properly hydrate to keep the body’s cooling system in excellent working order.

Our bodies are amazing machines designed to efficiently keep a stable body temperature. In fact there are 100 sweat glands on a quarter sized area of your skin. The average person has 2.6 million total sweat glands.

The hypothalamus in our brain is the area which detects changes in body temperature. Our muscles are like tiny furnaces and when the body temperature rises, the hypothalamus detects the increased temperature of the blood and the increased core temperature.

Body temperature can rise as much as three degrees during exercise causing the body’s natural cooling system to kick in to lower the temperature. Blood circulating near our skin surface pushes fluid out of our sweat glands where it cools (thermoregulation) and the evaporating fluid draws heat away from the blood vessels. The cooler blood then circulates through the body and lowers the overall temperature.

Sweating is a healthy function and necessary for life. The human body is composed of 60-75% water, therefore fluid balance is vital for keeping you functioning at optimum levels. Sweating helps regulate body temperature, cleans out pores, and releases toxins. However, problems can occur if fluid is not put back in your body.

Since sweat is made from fluid in the blood, the blood becomes thicker which makes the heart work harder to circulate blood throughout your body. If fluids are not replaced, dehydration can occur. Along with replacing water we need to replace the electrolytes lost after running.

With all this sweating that goes on while exercising, how can we make sure that we are replacing these fluids adequately?

Here are my Three Rules for Replenishing Fluids

  1. Don’t wait until you’re thirsty to replenish. By the time you feel thirsty, you may already be low on fluids.
  2. The best bet to accomplish adequate hydration is to drink before, during, and after your run. Let the duration, intensity, and climate conditions guide the amount.
  3. Don’t over-hydrate. In 2004 Runner’s World reported that 13% of runners in the Boston Marathon had hyponatremia (over-hydration)!

How to Calculate Your Fluid Needs

  1. Weigh nude before your run
  2. Run at race pace for 1 hour
  3. Track your fluid intake in ounces during the hour run
  4. Record nude weight after run and subtract it from your starting weight, convert the difference to ounces (1 pound= 16 oz)
  5. Determine your sweat rate by adding step #4 above to the total of fluids consumed
  6. To determine how much to drink every 15 minutes, divide results by the number 4 for a guideline
  7. Remember environmental conditions can change your fluid needs (heat or humidity)

Also Mentioned in this Episode

Born to Run by Christopher McDougall

Team in Training – run a marathon while raising money for a good cause

Tips for removing sweat odors from your running clothes

  • Wash your running clothes sooner rather than later. Don’t let odors get embedded!
  • Always wash technical fabrics in cold water. Hot water will break down the wicking ability of technical fabrics
  • I recommend washing your running clothes separately and using a sports detergent like Tide Sport, Gain, Nikwax, Penguin Sport, or Win High Performace Sport.
  • Never buy your running clothes second hand
  • A few other tips sent in by MTA listerners are: Wash clothes with a cap full of Pine Sol, Wash in white vinegar, and use Oxyclean detergent.

So what have you found to prolong the life of your running clothes?

13 Responses to Sweating and Hydrating 101

  1. Trevor July 10, 2010 at 5:38 pm #

    So what do you think? . . .

  2. Christina July 12, 2010 at 9:39 am #

    In Kansas, as you may know, our humidity level is high during this time of the season. During my short 3 mile run, I lost 1.2 lbs of fluid from sweating. One can only imagine what I looked/smelled like when I was done. Anyway, just wanted to let you know that I too am a very sweaty female. 🙂 Keep up the good work on your podcasts. I look forward to running to them!

  3. Angie July 14, 2010 at 1:52 pm #

    That’s amazing Christina! The heat and humidity really gets to me too. I’m counting the days until Fall. Happy sweating!

  4. Scott July 14, 2010 at 2:44 pm #

    Great PODCAST! I really don’t know where to start but since it’s all about sweating today I will choose there. I thought I was just a freak since I sweat like crazy! Seriously I take classes as part of my crosstraining and literally just a few minutes into the class I am drenched. Glad to know it has more to do with being fit and less the freak part. I just finished “Born to run” a few days ago and I also really liked it. I bought a pair of Vibram Five Fingers back in April and for the most part I love them. It took awhile to switch to fore foot running (my calves were screaming for a week or two) but once you get the hang of it the part of the book that describes running with your back straight and feet just “kissing” the ground makes sense. I am not a first time marathon runner but I do enjoy your show, keep them coming. By the way on a funny side note I started running in 1997 when my wife was pregnant with my son so I wouldn’t gain the “sympathy” weight, hahaha.

  5. Angie July 15, 2010 at 9:09 pm #

    Hey Scott,

    Thanks for the great comments. It’s always nice to hear from someone who deals with profuse sweating too 🙂 I loved the book “Born to Run” and am looking forward to trying some Vibram FiveFingers after having the baby and getting back into training. It’s good to hear your positive experience with them.

  6. Chris July 18, 2010 at 12:13 am #

    Great Podcast!

    The only downside is that I am now caught up to date on all of the ‘casts, and will have to wait for the next one!

    One note – It was mentioned in an earlier cast, but bears repeating that water with some carbs and electrolytes (eg – Sports Drink) is absorbed more quickly. It’s caused me to switch to half-strength sports drinks for my long (hot) runs!

  7. Angie July 19, 2010 at 11:30 am #

    Thanks Chris. You’re right, this hot weather is the perfect time to break out the sports drink! Keep up the great work.

  8. Jim July 23, 2010 at 2:40 pm #

    Thanks for the tips on electrolytes. My distances are now long enough that I need to manage electrolyte replenishment – but I haven’t until now. I am been steadily declining over last 4-5 days, starting with my last long run. Yesterday I got hyponatremia and nearly passed out after my run. WTF… I thought carbs…no, water intake…no, protein….no, potassium…no, but then I remember your specific words where you said you felt weak and lathargic…. and I thought, “it must be sodium level”. 10 min after ingesting sea salt, I felt better, 1.5 hrs later, totally like new! I have been aware of sodium and potassium replenishment, but it was your words that clued me into the symptoms in my then dulled mind. Thanks. Love the podcasts.

  9. Angie July 23, 2010 at 8:19 pm #

    Jim, I’m glad the podcast information came back to you right when you needed it. It’s important to use a sports drink with a good balance of carbs, potassium, and sodium especially during longer runs and in hot weather. Keep up the good work!

  10. Louise August 2, 2010 at 10:34 am #

    One tip I have about washing my running clothes….since I don’t do laundry everyday: I throw my clothes on the floor of the shower with me after a run to rinse them out! They may get a little soap or shampoo dripped on them too! I ring them out at the end of my shower and hang them to dry afterwards – even though they are not clean to put back in the drawer, I have gotten most of the sweat out and can wear them for another run before laundry day. This time of year, my clothes are drenched with sweat after a run and it is not a good idea to let that dry into the fabric. Its ironic that I take this kind of care of clothing that I only wear to get sweaty again!!!

  11. Angie August 2, 2010 at 12:56 pm #

    Great tip Louise. I’ll have to try that. I always hate putting sweaty clothes in the hamper knowing they won’t be washed for a few days.


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